GIANT NEGATIVE MAGNETORESISTIVITY IN WEAKLY COMPENSATED SEMICONDUCTORS

The ''giant'' negative magnetoresistivity (NMR) observed recently in d ifferent semiconductor samples in the regime of hopping conductivity w ith constant activation energy is explained in the frame of simple mod el, based on the impurity band structure of weakly doped and compensat ed semiconductors. It is shown, that the Zeeman splitting of the densi ty of impurity states and their repopulation in magnetic field result in the decrease of the activation energy of hopping conductivity and, consequently,in sufficient NMR. The numerical results for the temperat ure and magnetic field dependencies of NMR are presented. Copyright (C ) 1996 Published by Elsevier Science Ltd